U.S. patent application number 12/923845 was filed with the patent office on 2011-02-24 for printer with ink ribbon.
This patent application is currently assigned to CANON FINETECH INC. Invention is credited to Atsunobu Takatsuka.
Application Number | 20110043591 12/923845 |
Document ID | / |
Family ID | 36653384 |
Filed Date | 2011-02-24 |
United States Patent
Application |
20110043591 |
Kind Code |
A1 |
Takatsuka; Atsunobu |
February 24, 2011 |
Printer with ink ribbon
Abstract
A printer using a thermal head to sublime ink on an ink ribbon
includes a cylindrical ribbon core around which the ink ribbon is
wound, a rotating shaft to rotate the ribbon core, first and second
magnets to generate magnetic force lines in a space surrounded by
an inner peripheral face of the ribbon core, and a magnet sensor
located in the space to detect the magnetic force lines generated
by the first and second magnets only when the magnetic force lines
are set in prescribed directions by rotation of the ribbon core.
The ribbon core includes a cylindrical outer core with an outside
peripheral surface around which the ink ribbon is wound and a
cylindrical inner core with an outside peripheral surface to which
the first and second magnets are fixed. The inner core with the
first and second magnets fixed thereto is installed inside the
outer core.
Inventors: |
Takatsuka; Atsunobu;
(Mitsukaido-shi, JP) |
Correspondence
Address: |
KANESAKA BERNER AND PARTNERS LLP
1700 DIAGONAL RD, SUITE 310
ALEXANDRIA
VA
22314-2848
US
|
Assignee: |
CANON FINETECH INC
Mitsukaido-shi
JP
|
Family ID: |
36653384 |
Appl. No.: |
12/923845 |
Filed: |
October 12, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11297108 |
Dec 7, 2005 |
7857532 |
|
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12923845 |
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Current U.S.
Class: |
347/217 |
Current CPC
Class: |
B41J 35/36 20130101 |
Class at
Publication: |
347/217 |
International
Class: |
B41J 2/325 20060101
B41J002/325 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2004 |
JP |
2004-367593 |
Claims
1. A printer configured to use a thermal head to sublime ink on an
ink ribbon to form an image on a printing medium, the printer
comprising: a cylindrical ribbon core around which the ink ribbon
is wound; a rotating shaft configured to rotate the ribbon core; a
first magnet and a second magnet each configured to generate a
magnetic force line in a space surrounded by an inner peripheral
face of the ribbon core, and a magnet sensor located in the space
surrounded by the inner peripheral face of the ribbon core and
configured to detect the magnetic force lines generated by the
first and second magnets only when the magnetic force lines are set
in prescribed directions by rotation of the ribbon core, wherein
the ribbon core comprises a cylindrical outer core with an outside
peripheral surface around which the ink ribbon is wound and a
cylindrical inner core with an outside peripheral surface to which
the first and second magnets are fixed, and the inner core with the
first and second magnets fixed thereto is installed inside the
outer core.
2. The printer according to claim 1, wherein the outer core and
inner core of the ribbon core are each a non-magnetic material.
3. The printer according to claim 1, wherein the magnetic sensor
detects the magnetic force lines every time the ribbon core makes
one rotation.
4. The printer according to claim 1, wherein first magnet is fixed
to a limited portion of the outside peripheral surface of the inner
core, and the second magnet is fixed to an opposite portion of the
outside peripheral surface of the inner core which portion is
opposite the limited portion.
5. The printer according to claim 4, wherein the first magnet is
fixed to a first depression formed in the limited portion of the
outside peripheral surface of the inner core, and the second magnet
is fixed to a second depression formed in the opposite portion of
the outer peripheral surface of the inner core.
6. A printer configured to use a thermal head to sublime ink on an
ink ribbon to form an image on a printing medium, the printer
comprising: a cylindrical ribbon core around which the ink ribbon
is wound; a rotating shaft fitted inside the cylindrical ribbon
core to rotate the ribbon core; a first magnet and a second magnet
each configured to generate a magnetic force line in a space
surrounded by an inner peripheral face of the ribbon core, and a
magnet sensor fixedly located inside the rotating shaft to detect
the magnetic force lines generated by the first and second magnets
only when the magnetic force lines are set in prescribed directions
by rotation of the ribbon core, wherein the first and second
magnets are fixed to a central portion of the cylindrical ribbon
core in a height direction thereof, and the magnetic sensor is
fixed to a central portion of the rotating shaft in a longitudinal
direction thereof.
7. The printer according to claim 6, wherein the ribbon core
comprises a cylindrical outer core including an outside peripheral
surface formed thereon and around which the ink ribbon is wound;
and a cylindrical inner core including an inside peripheral surface
formed thereon and inside which the rotating shaft is fitted and an
outer peripheral surface also formed thereon and to which the first
and second magnets are fixed, the inner core being installed inside
the outer core.
8. The printer according to claim 7, wherein the first magnet is
fixed to a limited portion of the outside peripheral surface of the
inner core, and the second magnet is fixed to an opposite portion
of the outside peripheral surface of the inner core which portion
is opposite the limited portion.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a divisional application of Ser. No. 11/297,108
filed on Dec. 7, 2005.
TECHNICAL FIELD
[0002] The present invention relates to a printer with an ink
ribbon unit having cylindrical ribbon cores for winding an ink
ribbon around the outside peripheral face thereof.
TECHNICAL BACKGROUND
[0003] Thermal transfer type printers are known which form (or
print) an image on a recording medium (paper sheet) by
pressure-contacting a thermal head against a peripheral face of a
platen roller with interposition of the recording medium and an ink
ribbon. In the thermal transfer type printer, an ink ribbon
cassette is set removably in which an ink ribbon of a predetermined
width is wound around a cylindrical ribbon cores. In the ink ribbon
cassette, a ribbon-delivery core holds an unused ink ribbon wound
around it and delivers the ink ribbon, and another core, a
ribbon-winding-up core, winds up the used ink ribbon.
[0004] In the image formation by the printer, a platen roller is
rotated at a constant rotation speed to deliver the ink ribbon at a
constant delivery speed from the ink ribbon-delivery core. The
ribbon-delivery core, while holding a sufficient amount of the
unused ink ribbon wound thereon, is rotated at a low rotation speed
since the outside diameter of the wound ribbon is large. With
progress of delivery of the ink ribbon from the ribbon-delivery
core, the outside diameter of the wound ribbon gradually decreases
to increase gradually the rotation speed of the ribbon-delivery
core. In contrast, on the ribbon-winding-up core, the outside
diameter of the wound ribbon increases with progress of the
delivery of the ribbon from the ribbon-delivery core, resulting in
gradual decrease of the rotation speed thereof.
[0005] Accordingly, the amount of the remaining unused ink ribbon
can be estimated by measurement of the rotation speed of the
ribbon-delivery core (or the ribbon-winding-up core) to estimate
the outside diameter of the wound ribbon. For measurement of the
rotation speed, in a known technique, a flange having a magnetic
member is provided at a lengthwise end of the ribbon core, and the
rotation speed is measured by detecting the magnetic force lines
generated by the magnetic member (e.g., Japanese Patent Laid-Open
No. 2003-211801)
DISCLOSURE OF THE INVENTION
[0006] In the above known technical method, a flange having a
magnetic member is provided on the ribbon core and the rotation
speed is measured by detecting the magnetic force lines generated
by the magnetic member. In this constitution, parts or a member of
the ink ribbon unit may be placed between the magnetic sensor and
the flange, which necessitates a stronger magnetic force of the
magnetic member. The stronger magnetic force may attract a clip, a
staple or the like to cause adhesion thereof to the flange. The
clip or the like adhering to the ribbon core flange not removed, on
setting the ink ribbon unit on the printer main body, may cause
inconvenience in the ink ribbon unit, or the clip dropped in the
main body of the printer may cause disorder of the printer.
[0007] In winding up the ink ribbon around the cylindrical ribbon
core, the flange of the ribbon core can obstruct the winding
operation. Further, with the flanged core, the ink ribbon should be
cut and removed in the width corresponding to the flange thickness
in winding up the ink ribbon around the ribbon core to cause waste
of the part of the ribbon and to cause an increase of cost.
[0008] Under the above circumstances, the present invention intends
to provide a printer with a thermal head using an ink ribbon unit
which enables estimation of the amount of the remaining unused ink
ribbon without providing a flange on the ribbon core and does not
cause inconvenience of the ribbon unit or disorder of the printer
main body. The present invention intends also to provide a quick
method for judgment of occurrence of ink ribbon jamming.
SUMMARY OF THE INVENTION
[0009] The ink ribbon unit of the present invention is provided
with a cylindrical ribbon core which has an outside peripheral face
for winding up an ink ribbon of a prescribed width and rotates in
the direction of the peripheral face, comprising
(1) a magnetic force-generating means for generating magnetic force
lines directed from a first limited portion of the inside
peripheral face of the ribbon core toward a second limited portion
thereof opposing to the first limited portion, and (2) a magnetic
sensor for detecting the magnetic force lines generated by the
magnetic force-generating means only when the direction of the
magnetic force lines comes to coincide with a predetermined
direction. (3) The magnetic force-generating means may comprise
(3-1) a first magnet fixed onto the first limited portion of the
ribbon core, and (3-2) a second magnet fixed onto the opposing
second limited portion of the ribbon core to form magnetic force
lines in combination with the first magnet. (4) The magnetic sensor
may be fixed onto a position surrounded by the inside peripheral
face of the ribbon core. (5) The ribbon core may be made of a
non-magnetic material, and (6) the ribbon core may be magnetized
only at the first limited portion and the opposing second limited
portion. (7) The first magnet and the second magnet may be
distinguishable visually. (8) The magnetic sensor may detect the
magnetic force lines in every one rotation of the ribbon core. (9)
The magnetic sensor may detect the magnetic force lines in every
half rotation of the ribbon core.
[0010] A method for judgment of ink ribbon jamming of the present
invention comprises
(10) generating magnetic force lines invariably in the direction
from a first limited portion of the inside wall face of the ribbon
core toward an opposing second limited portion thereof, with
rotation of a cylindrical ribbon core having an outside peripheral
face with a ribbon of a predetermined width wound thereon, (11)
detecting only the magnetic force lines in a predetermined
direction, and (12) judging occurrence of the ink ribbon jamming
from a time interval of detection of the magnetic force lines.
[0011] Another method of judging ink ribbon jamming of the present
invention comprises
(13) generating magnetic force lines invariably in the direction
from a first limited portion of the inside face of the ribbon core
toward an opposing second limited portion thereof with rotation of
a cylindrical ribbon core having an outside peripheral face with a
ribbon of a predetermined width wound thereon, and simultaneously
generating a constant pulse, (14) detecting only the magnetic force
lines in a predetermined direction, (15) counting the number of the
pulse in a time interval of detection of the magnetic force lines,
and (16) judging occurrence of the ink ribbon jamming from the
count number of the pulse. (17) In judgment of occurrence of the
ink ribbon jamming from the counted number of the pulse, the ink
ribbon jamming may be judged to have occurred when the counted
number of the pulse is larger than a prescribed maximum number.
(18) In judgment of occurrence of the ink ribbon jamming from the
counted number of the pulse, (19) two pulse numbers detected in
successive two time intervals of the magnetic force line detection
are compared, and (20) the ink ribbon jamming may be judged to have
occurred when the difference in the counted numbers of the pulse is
larger than a prescribed number. (21) In judging the ink ribbon
jamming from the counted number of the pulse, (22) during the time
period from start of the rotation of the ribbon core to rotation to
a prescribed accumulated rotation number, the ink ribbon jamming
may be judged to have occurred when the counted number of the pulse
is larger than a prescribed maximum number, and (23) after the
rotation to the prescribed accumulated rotation number of the
ribbon core, two pulse numbers of successive two time intervals of
the magnetic force line detection are compared, and (24) the ink
ribbon jamming may be judged to have occurred when the difference
in the counted numbers of the pulse is larger than a prescribed
number.
[0012] A printer of the invention is configured to use a thermal
head to sublime ink on an ink ribbon to form an image on a printing
medium. The printer comprises
[0013] a cylindrical ribbon core around which the ink ribbon is
wound;
[0014] a rotating shaft configured to rotate the ribbon core;
[0015] a first magnet and a second magnet each configured to
generate a magnetic force line in a space surrounded by an inner
peripheral face of the ribbon core, and
[0016] a magnet sensor located in the space surrounded by the inner
peripheral face of the ribbon core and configured to detect the
magnetic force lines generated by the first and second magnets only
when the magnetic force lines are set in prescribed directions by
rotation of the ribbon core.
[0017] The ribbon core comprises a cylindrical outer core with an
outside peripheral surface around which the ink ribbon is wound and
a cylindrical inner core with an outside peripheral surface to
which the first and second magnets are fixed. The inner core with
the first and second magnets fixed thereto is installed inside the
outer core.
[0018] In the ink ribbon unit of the present invention, the
magnetic force-generating means generates magnetic force lines
directed from a first limited portion of the internal face of the
ribbon core toward a second limited portion thereof opposing to the
first limited portion, so that the amount of the remaining unused
ribbon can be estimated without providing a flange attached to the
ink ribbon core. Further, since no flange attracting a magnetizable
matter is employed, neither inconvenience of the ink ribbon unit
nor disorder of the printer main body will not be caused.
[0019] According to the method for judging occurrence of the ribbon
jamming of the present invention, an ink ribbon jamming is judged
by generating magnetic force lines constantly in the direction from
a first limited portion of the inside face of the ribbon core
toward an opposing second limited portion thereof, detecting only
the magnetic force lines in a predetermined direction, and judging
occurrence of the ink ribbon jamming from a time interval between
successive detection of the magnetic force lines. Therefore, the
ink ribbon jamming can be judged quickly. The recording medium can
cause jamming also by jamming of the ink ribbon. Therefore, the
jamming of the recording medium can also be judged quickly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 illustrates schematically an outline of a printer
incorporating an ink ribbon unit of the present invention.
[0021] FIG. 2 is a cross-sectional view of a part of the
ribbon-delivery core of the ribbon unit shown in FIG. 1.
[0022] FIGS. 3A and 3B are cross-sectional views showing relative
positions of the ribbon core having two magnets fixed thereon and
the magnetic sensor, wherein FIG. 3A shows the state in which the
direction of the magnetic force lines coincides with the
predetermined direction (detection direction), and FIG. 3B shows a
state in which the direction of the magnetic force lines is
different from the predetermined direction.
[0023] FIG. 4 is a cross-sectional view of the ribbon core of
comparative example in which four magnets are fixed on the ribbon
core.
[0024] FIG. 5 is a perspective view showing assemblage of the
ribbon core.
[0025] FIGS. 6A and 6B are schematic drawings showing a method for
differentiating two kinds of the ribbon core magnets.
[0026] FIGS. 7A and 7B illustrate schematically a method of winding
an ink ribbon around the ribbon core of the constitution of FIG. 5,
wherein FIG. 7A is a front view, and FIG. 7B is a side view.
[0027] FIGS. 8A and 8B illustrate schematically a method of winding
an ink ribbon around a ribbon core of the ink ribbon unit of a
comparative example, wherein FIG. 8A is a front view, and FIG. 8B
is a side view.
[0028] FIG. 9 is a block diagram showing a jam-judging unit for
judging jamming of the ink ribbon.
[0029] FIG. 10 is a flow chart showing an example of the steps for
judging jamming of the ink ribbon.
DETAILED DESCRIPTION OF THE INVENTION
[0030] The present invention has been achieved for a thermal
transfer type printer which forms an image on a recording medium by
pressing a thermal head against a platen roller with interposition
of an ink ribbon and a recording medium.
Example 1
[0031] A printer incorporating an ink ribbon unit of the present
invention is explained by reference to FIG. 1.
[0032] FIG. 1 illustrates schematically a printer incorporating an
ink ribbon unit of the present invention.
[0033] The printer 10 is a thermal transfer type printer which
forms (prints) an image by pressing a thermal head 14 against a
peripheral face of a platen roller 12 rotating in the arrow-A
direction with interposition of a recording medium (printing medium
like a tube or a tape) and an ink ribbon 42. Into this thermal
transfer type printer 10, an ink ribbon cassette 40, is inserted
removably. The ink ribbon cassette 40 has cylindrical ribbon cores
50,60 carrying an ink ribbon 42 of a predetermined width (length in
the direction perpendicular to the paper sheet face of FIG. 1)
wound between the ribbon cores. The ribbon cores 50,60 include a
ribbon-delivery core 5.0 for delivering an unused portion of the
ink ribbon wound thereon and a ribbon-winding-up core 60 for
winding up the ribbon delivered from the ribbon delivery core 50
and having been used for the printing. In image formation on a
printing medium with the printer 10, the platen roller 12 is
rotated at a constant rotation speed to deliver the printing medium
nipped between the platen roller 12 and a driven roller 13 at a
constant delivery rate, and to deliver the ink ribbon 42 at a
constant delivery rate from the ribbon delivery core 50.
[0034] The printing medium is fed in the arrow-B direction and is
discharged in the arrow-C direction. The printing medium fed in the
arrow-B direction is nipped and delivered between the delivery
roller 16 and the driven roller 18. The driven roller 18 is
constructed to be displaced in connection with the opening-closing
movement of a cover (not shown in the drawing). By opening the
cover, the driven roller 18 is displaced from the position
indicated by the solid line to another position indicated by the
two-dot chain line to be separated from the delivery roller 16 to
facilitate insertion of the printing medium as shown in the
drawing. By closing the cover, the driven roller 18 is moved to the
position for pressing the delivery roller 16 to deliver the
printing medium surely between the two rollers 16,18. The printing
medium after the image formation is cut in a suitable length by a
cutter 20 and a cutting block 22, and is discharged in the arrow-C
direction. The printing medium includes label tapes, flattened
tubes, 4-mm ID (index), and so forth. Such a printing medium is
wound and enclosed in a single-purpose cassette (not shown in the
drawing).
[0035] A magnetic sensor 24 is fixed to the main body of the
printer 10. This magnetic sensor 24 detects only magnetic force
lines in a predetermined direction. With the ribbon cassette 40 set
in the main body of the printer 10, the magnetic sensor 24 is
placed at the center of the space surrounded by the inside
peripheral wall face of the cylindrical ribbon-delivery core 50. In
this example, the ink ribbon unit of the present invention is
constituted of the aforementioned ink ribbon cassette 40 and the
magnetic sensor 24. By setting the ink ribbon cassette 40 in the
main body of the printer 10, a rotation axis (not shown in the
drawing) is inserted respectively into the inside space (surrounded
by the inside wall face) of the ribbon-delivery core 50 and that of
the ribbon-winding-up core 60. Thereby the ribbon-delivery core 50
and the ribbon-winding-up core 60 are rotated at a predetermined
rotation speed. On the other hand, the magnetic sensor 24 is fixed
immovably onto a separate axis other than the above rotation axes
on the main body of the printer 10.
[0036] The ribbon-delivery core 50 of the ink ribbon cassette 40 in
FIG. 1 is explained by reference to FIG. 2.
[0037] FIG. 2 is a cross-sectional view of a part of the
ribbon-delivery core of the ink ribbon unit shown in FIG. 1. In
FIG. 2, the same reference symbols as in FIG. 1 are used for
denoting corresponding constitutional elements.
[0038] The ribbon-delivery core 50 is cylindrical in the shape as
mentioned above. A magnetic force lines 51 are generated between a
portion (a first portion) of the inside wall face 50a and the
opposite portion (a second portion) thereof. A first magnet 52 is
fixed onto the first portion, and a second magnet 54 is fixed in
the opposite second portion. The first magnet 52 has its N pole on
the inside wall face 50a and its S pole on the outside peripheral
face 50b. The second magnet has its S pole on the inside wall face
50a and its N pole fixed on the outside peripheral face 50b.
Therefore, inside the ribbon-delivery core 50 (the space surrounded
by the inside wall face 50a), a magnetic force lines 51 are
generated in the direction from the N pole of the first magnet 52
to the S pole of the second magnet 54.
[0039] When the ink ribbon cassette 40 is taken out from the main
body of the printer 10, a foreign matter 82 such as a clip dropped
on the floor 80 cannot be attracted by the magnetic force to the
ribbon cassette 40, since the first magnet 52 and the second magnet
54 are placed inside apart from the casing of the ink ribbon
cassette.
[0040] In the state that the ink ribbon cassette 40 is set to the
main body of the printer 10, the magnetic sensor 24, which is
positioned at the inside center portion of the ribbon-delivery core
50, detects the magnetic force lines 51. This detection is
explained by reference to FIGS. 3 and 4.
[0041] The magnetic force lines and detection thereof in the ribbon
core of FIG. 2 is explained by reference to FIGS. 3 and 4.
[0042] FIGS. 3A and 3B are cross-sectional views showing the
positional relation between the ribbon core having two magnets and
the magnetic sensor. FIG. 3A illustrates the magnetic force in the
predetermined direction (detectable direction), and FIG. 3B
illustrates the magnetic force not in the predetermined direction
(not detectable). FIG. 4 is a cross-sectional view of the ribbon
core of the comparative example in which four magnets are
employed.
[0043] The magnetic sensor 24 has a detection element 24a for
detecting magnetic force lines. The detection element 24a includes
two types: two-pole detection type element which is capable of
differentiating the positions of the N pole and the S pole (capable
of differentiating the direction of the magnetic lines); and
one-pole detection type element which is capable of detecting
magnetic force lines but incapable of differentiating the positions
of the N pole and the S pole. With either type of the detection
element 24a, the magnetic force lines 51 are detected by the
detection element 24a, only when the direction of the magnetic
force lines 51 comes to coincide with the predetermined direction
(detection direction) as shown in FIG. 3A. Here, the detection
direction signifies the direction of the magnetic force lines 51
shown in FIG. 3A and the direction reverse thereto. The magnetic
force lines 51 in the direction different from the predetermined
direction (detection direction) are not detected by the detection
element 24a.
[0044] Therefore, with the detection element 24a of the two-pole
detection type, during one rotation of the ribbon-delivery core 50
in its periphery direction (arrow-D direction), the magnetic force
lines 51 are detected twice in reversed directions. That is, the
magnetic force lines 51 are detected by differentiating the
direction once in half rotation in the periphery direction (in the
arrow-D direction) of the ribbon-delivery core 50. On the other
hand, with the detection element 24a of the one-pole detection
type, the magnetic force lines 51 are detected without
differentiating the direction once in half rotation in the
periphery direction (in the arrow-D direction) of the
ribbon-delivery core 50. In the above examples, the magnetic force
is designed to be generated inside the ribbon-delivery core 50.
Otherwise, the magnetic force may be designed to be generated
inside the ribbon-winding-up core 60.
[0045] In the above ribbon-delivery core 50, two magnets 52,54 are
placed in opposition to generate the magnetic lines within the
ribbon-delivery core 50. Instead, three or more magnets could be
employed. For example, as shown in FIG. 4, four magnets
151,152,153,154 could be employed in equal intervals along the
periphery in the ribbon-delivery core 150. However, with the four
magnets, the magnetic force lines 155 can be directed to the
adjacent magnets to prevent the detection of the magnetic force
lines by the magnetic sensor 24. Therefore, only two magnets 52,54
are provided in the opposing positions.
[0046] An example of the process for preparing the ribbon core is
explained by reference to FIGS. 5 and 6.
[0047] FIG. 5 is a perspective view illustrating the process for
assembling the ribbon core. FIG. 6 shows schematically a method for
differentiating the kinds of the ribbon core magnets. In these
drawings, the same symbols as in FIG. 3 are used for denoting
corresponding elements.
[0048] The ribbon-delivery core 50 is constituted of an inner core
58 and an outer core 59, respectively made of a non-magnetic
material. The inner core 59 has an outside diameter slightly
smaller than the inside diameter of the outer core 59. The two
cores 58,59 have nearly the same height. The inner core 58 has a
depression 58a for bonding of the first magnet 52 and a second
depression (not shown in the drawing) for bonding of the second
magnet 54. The first magnet 52 is bonded to the depression 58a, and
the second magnet 54 is bonded to the second depression similarly.
Then the outer core 59 is fitted outside the inner core 58. Thereby
the ribbon-delivery core 50 is prepared in which the first magnet
52 and the second magnet 54 are fixed, and the intended opposing
positions only are magnetized.
[0049] The first magnet 52 and the second magnet 54 cannot usually
be differentiated visually from each other. To facilitate the
visual differentiation between the first magnet 52 and the second
magnet 54, the N pole side surfaces of the first and second magnets
are embossed as shown in FIG. 6 without embossing the S pole side
surface. Thereby the error in assemblage can be prevented, even
when the first magnets 52 and the second magnets 54 are stored
mixedly in a large number.
[0050] A method is explained for winding an ink ribbon around a
ribbon core having the structure shown in FIG. 5 by reference to
FIGS. 7 and 8.
[0051] FIG. 7 illustrates schematically a method for winding an ink
ribbon around a ribbon core having the structure shown in FIG. 5.
FIG. 7A is a front view, and FIG. 7B is a side view. FIG. 8
illustrates schematically a method for winding an ink ribbon around
a ribbon core in the ink ribbon unit of comparative example. FIG.
8A is a front view, and FIG. 8B is a side view.
[0052] For winding the ink ribbon 42 (FIG. 1) around the
ribbon-delivery core 50, there are prepared a long core 159
constituted of connection of several units of the outer core 59,
and a wide ink ribbon 142 having nearly the same width as that of
the long core 159. This wide ink ribbon 142 is wound around the
outside peripheral face of the long core 159 by rotating the long
core by a rotation device (not shown in the drawing) by cutting the
broad ink ribbon 142 in a width of the intended ink ribbon 42.
After winding up the intended length of the ink ribbon 42, the long
core 159 having the cut and wound ink ribbons 42 is divided into
the unit cores having the length of the outer core 59. Thereby, the
plural outside cores 59 carrying the ink ribbon can be obtained
readily. Thereafter, as explained by reference to FIG. 5, the
ribbon-delivery core 50 can be prepared readily which has an ink
ribbon 42 wound around.
[0053] In contrast, in the case where the employed outer core 69
has a flange 69a as shown in FIG. 8, the wide ribbon is wound by
cutting and discarding a portion of the wide ink ribbon 142
corresponding to the thickness t of the flange 69a. This increase
the waste of the wide ink ribbon 142, and the flange 69a hinders
the winding operation and lowers the operation efficiency.
[0054] A technique of judgment of ink ribbon jamming is explained
by reference to FIGS. 9 and 10.
[0055] FIG. 9 is a block diagram of the jam-judgment unit for
judging the ink ribbon jamming. FIG. 10 is a flow chart showing an
example of a procedure for judgment, of ink ribbon jamming.
[0056] The jam-judgment unit 200 comprises a pulse generator 202; a
time-measuring device 204 for measuring the time interval of the
detection of magnetic force lines (magnetic field) by a magnetic
sensor 24 (FIG. 1, etc.); a pulse counter 206 for counting the
pulses generated by the pulse generator 202 during the time of
measurement by the time-measuring device 204; and the above
magnetic sensor 24. The pulse generator 202, the time-measuring
device 204, and the pulse counter 206 are built in the main body of
the printer 10 (FIG. 1, etc.). An example of the number of the
pulse generated by the pulse generator 202 at constant time
intervals is a pulse number of 1500, generated during one rotation
of the ribbon-delivery core 50 carrying ink ribbon 42 (FIG. 1)
fully wound (before use of the ink ribbon).
[0057] A signal of detection of magnetic force lines 51 by the
magnetic sensor 24 (FIG. 1, etc.) is sent to CPU 208. The CPU 208
drives a pulse counter 206 in accordance with the received signal.
On judging the jamming of the ink ribbon 42 (occurrence of ribbon
jamming), the CPU displays a message of "Jamming" on a control
panel 210.
[0058] In an example, the judgment of ink ribbon jamming is based
on a time interval of detection of magnetic force lines 51 (FIG. 3,
etc.) by the magnetic sensor 24. This time interval is measured by
the time-measuring device 204. With the ribbon-delivery core 50, at
the beginning of the use of the ribbon 42, the core is rotated
slowly owing to a large amount of the unused wound ribbon 42. The
rotation becomes gradually faster with use of the ink ribbon. When
the ink ribbon 42 jams, the delivery of the ink ribbon 42 is
retarded, causing sudden decrease of the rotation rate of the
ribbon-delivery core 50. Therefore the jamming of the ink ribbon 42
is judged by the aforementioned time interval.
[0059] On the other hand, in the case where the first magnet 52 and
the second magnet 54 are installed in the ribbon-winding-up core 60
for detection of ribbon jamming, the phenomenon is reverse to the
case of the ribbon-delivery core 50. At the beginning of the use of
the ribbon, the ribbon-winding-up core 60 is rotated fast owing to
absence of the wound ribbon 42. The rotation becomes gradually
slower with gradual increase of the wound ribbon after use. When
the ink ribbon 42 jams, the delivery of the ink ribbon 42 is
retarded, causing sudden decrease of the rotation rate of the
ribbon-winding-up core 60. Therefore the jamming of the ink ribbon
42 is judged by the aforementioned time interval.
[0060] Another example of detection of the jamming of the ink
ribbon is explained by reference to FIG. 10.
[0061] This flow of the operation is started by turning on the
power source of the printer 10 to drive the main motor to rotate
the ribbon-delivery core 50. With power application to the printer
10, are driven the pulse generator 202, the time-measuring device
204, the pulse counter 206, the CPU 208, the magnetic sensor 24,
and so forth. In this example, the magnetic sensor 24 is of the
above-mentioned two-pole detection type. In every half rotation
time of the ribbon-delivery core 50, the number of the pulse is
counted by the pulse counter 206. In this example, the pulse
generator 202 generates pulse of 1500 during the time of one
rotation of the ribbon-delivery core 50 carrying the ink ribbon 42
(FIG. 1) fully wound (unused rink ribbon).
[0062] Firstly, after start of rotation of the ribbon-delivery core
50, the pulse counter 206 counts the number of the pulses in half
rotation of the core to judge whether or not the pulse number is
not less than 1500 (S1001). The detected pulse number of not less
than 1500 signifies that the rotation speed of the ribbon-delivery
core 50 is less than the normal rotation speed of the core 50
carrying a fully wound ribbon, indicating possibility of jamming of
the ribbon 42 (or the printing medium) (S1002). Then the main motor
is stopped (S1003), and the control panel 210 displays requirement
for inspection of the ink ribbon cassette 40 (S1004).
[0063] The detected pulse number of less than 1500 signifies that
the rotation speed of the ribbon-delivery core 50 becomes higher
owing to gradual delivery of the ink ribbon 42. This pulse number
is memorized in the memory 211 (S1005). Then detection of magnetic
force lines by the magnetic sensor 24 is examined (S1006) to judge
whether the ribbon-delivery core 50 has turned one rotation. When
the rotation is less than the one complete rotation, the operation
flow is returned to S1001. When the one rotation is judged to have
been completed in S1006, the pulse number counted in a first half
rotation after start of the rotation of the ribbon-delivery core 50
(the counted pulse number in the first half rotation) and the pulse
number counted in a second half rotation next to the above first
half rotation (the counted pulse number in the second half
rotation) are compared with each other. This comparison is made by
CPU 208. Then the difference in the counted pulse numbers between
the first half rotation and the second half rotation is examined to
judge whether the difference is not less than 100 (S1007). The
difference in the counted pulse numbers of not less than 100 shows
sudden slow-down of the rotation speed of the ribbon-delivery core
50, suggesting occurrence of jamming of the ink ribbon 42. Then the
operation flow is returned S1002 to conduct the steps of S1003 and
S1004.
[0064] The difference of less than 100 detected in S1007 shows
normal rotation of the ribbon-delivery core 50 without jamming of
the ink ribbon 42. In this case, the above pulse number in the
second half rotation is memorized in the memory 211 (S1008) to
replace the pulse number in the first half rotation by the pulse
number in the second half rotation. Further the operation is
returned to S1001, and the pulse number in half rotation of the
ribbon-delivery core 50 is examined whether the pulse number is not
less than 1500.
[0065] As described above, jamming of the ink ribbon 42 can be
detected by examining the magnetic force lines 51 with the magnetic
sensor 24.
* * * * *